The Digital Visual Interface (DVI) is widely accepted as the standard digital interface for digital display devices like flat panels. The Digital Display Working Group (DDWG) developed the specification for DVI. DVI uses Silicon Image's PanelLink technology, which is a high-speed serial interface that uses transition minimized differential signaling (TMDS) to send data to the monitor.
Transition minimized refers to a reduction in the number of high-to-low and low-to-high swings on a signal. Differential describes the method of transmitting a signal using a pair of complementary signals. The encoding uses logic to minimize the number of transitions, which helps avoid excessive electromagnetic interference levels on the cable, thereby increasing the transfer rate and improving accuracy.
DVI allows for two TMDS logical links according to a specification, called Dual-Link. Each link is composed of 3 differential data pair (RGB+control signals), shares a differential clock pair and, using the present standard, has a maximum bandwidth of 165 MHz for a single link and 330 MHz for two links. The DVI specification requires that once a mode requires a pixel clock greater than 165 MHz, then it must use the second link as well. The two links share the same clock so that the bandwidth is evenly divided between them. The system enables one or both links, depending on the capabilities of the monitor. Dual-Link uses a first one of the data links to transmit odd pixels and the second data link to transmit even pixels.
DVI also takes advantage of other features built into existing display standards. For example, provisions are made for Extended Display Identification Data (EDID) specifications, which enable the monitor, graphics adapter, and computer to communicate and automatically configure the system to support the different features available in the monitor.
In the state of the art, Dual-Link allows for high-resolution display on one output device. There is a need to drive two flat panel screens together, but to have their displays independent from each other. This need is fed by the desire for more ergonomic work areas with displays of increased real estate. The cost of buying two 15 inch monitors is significantly low compared to the cost of buying one 19 inch monitor. Similarly, a flat panel screen takes up a lot less room on a work area, such as a desk, than a standard monitor does.
Moreover, the digital panel display market is growing from month to month. With the pressure on graphics adapter manufacturers to produce products for the digital panel market, there is a growing need for a system that can accommodate not only one digital display, but also two simultaneous ones with independent images.